From 3dd8e596812e3adb72aecafb23fbb6a30836c475 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 4 Jun 2012 20:43:57 -0400
Subject: [PATCH] Fix bogus handling of control characters in
 json_lex_string().

The original coding misbehaved if "char" is signed, and also made the
extremely poor decision to print control characters literally when trying
to complain about them.  Report and patch by Shigeru Hanada.

In passing, also fix core dump risk in report_parse_error() should the
parse state be something other than what it expects.
---
 src/backend/utils/adt/json.c       | 8 ++++----
 src/test/regress/expected/json.out | 3 +--
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index 8ab47defbe4..61ae62eb8a9 100644
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -419,7 +419,7 @@ json_lex_string(JsonLexContext *lex)
 	for (s = lex->token_start + 1; *s != '"'; ++s)
 	{
 		/* Per RFC4627, these characters MUST be escaped. */
-		if (*s < 32)
+		if ((unsigned char) *s < 32)
 		{
 			/* A NUL byte marks the (premature) end of the string. */
 			if (*s == '\0')
@@ -430,8 +430,8 @@ json_lex_string(JsonLexContext *lex)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 					 errmsg("invalid input syntax for type json"),
-					 errdetail_internal("line %d: Character \"%c\" must be escaped.",
-						lex->line_number, *s)));
+					 errdetail_internal("line %d: Character with value \"0x%02x\" must be escaped.",
+						lex->line_number, (unsigned char) *s)));
 		}
 		else if (*s == '\\')
 		{
@@ -637,7 +637,7 @@ report_parse_error(JsonParseStack *stack, JsonLexContext *lex)
 			(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 			 errmsg("invalid input syntax for type json: \"%s\"",
 				lex->input),
- 			 errdetail_internal(detail, lex->line_number, token)));
+			 detail ? errdetail_internal(detail, lex->line_number, token) : 0));
 }
 
 /*
diff --git a/src/test/regress/expected/json.out b/src/test/regress/expected/json.out
index ed8b2370762..4b1ad89de6e 100644
--- a/src/test/regress/expected/json.out
+++ b/src/test/regress/expected/json.out
@@ -26,8 +26,7 @@ def"'::json;					-- ERROR, unescaped newline in string constant
 ERROR:  invalid input syntax for type json
 LINE 1: SELECT '"abc
                ^
-DETAIL:  line 1: Character "
-" must be escaped.
+DETAIL:  line 1: Character with value "0x0a" must be escaped.
 SELECT '"\n\"\\"'::json;		-- OK, legal escapes
    json   
 ----------
-- 
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